JPS6225935B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention improves the usability of a combustion machine, such as a heater, in which flame detection is performed using a flame rod and information on ``ignition'' and ``combustion'' is sent to a control circuit for sequence control. It is something that makes things better.

The present invention is a combustion machine (heating machine) that is equipped with a flame detection circuit that ignites vaporized fuel with an igniter such as an igniter and detects the flame by the ionic current of the flame.
If so, it can be effectively used for all kinds of things, but here we will explain it using an oil gasification fan heater as an example. FIG. 1 is a schematic cross-sectional configuration diagram of the fan heater.

In the figure, reference numeral 1 denotes a combustion air blowing pipe for blowing combustion air into the vaporizing cylinder 4 by means of a combustion fan 3 attached to a combustion blower 2, with an adjustment knob 5 interposed therebetween for adjusting the amount of air blown. There is. Reference numeral 6 denotes a bypass pipe that branches off from the combustion air blowing pipe 1 and communicates with the vaporizing cylinder 4, and has a fine adjustment knob 7 interposed therebetween for finely adjusting the amount of air blown. Reference numeral 8 denotes an oil leveling device that stores a certain amount of kerosene supplied from an oil tank (not shown), and an air chamber 9 with a certain capacity is provided in the upper part. A pressure conducting pipe 10 branched from the air blowing pipe 1 is in communication. 11 is disposed at the center of the combustion air pipe 1 with one end 13 opening into the kerosene chamber 12 of the oil level regulator 8 and passing through the upper wall surface 14 of the air chamber 9; This is a fuel nozzle whose tip end 15 opens into an opening 16 of the combustion air pipe 1 in the vaporization tube 4 . The opening 16 is a spray nozzle 16' whose tip is tapered and has a small diameter.
is formed. Reference numeral 17 is provided in close proximity to the bottom of the vaporization tube 4, and is used to vaporize the inside of the vaporization tube 4 in advance in order to instantaneously vaporize and burn the mixed gas of the combustion air and the fuel sprayed from the fuel nozzle 11. This is a preheater that heats to the optimum temperature. 18 is a burner head provided at the upper part of the vaporizing cylinder 4.

Next, the operation of the fan heater having the above configuration will be explained. First, when the combustion blower 2 is operated, the combustion air is adjusted by the combustion fan 3 by the adjustment knob 5, and the combustion air blower pipe 1 is heated.
The air is blown to the opening 16 of the vaporizer cylinder 4 through the air. At the same time, the blowing pressure generated in the combustion air blower pipe 1 is transmitted to the air chamber 9 of the oil level regulator 8 through the pressure conduction pipe 10, and the kerosene in the kerosene chamber 12 in the oil level regulator 8 is used as fuel. The fuel in the fuel nozzle 11 is pushed up into the nozzle 11 and is blown into the vaporization tube 4 from the tip 15 by the air blown from the combustion air blowing pipe 1 at the opening 16 of the vaporization tube 4. It is attached and atomized using the ``atomizing principle.'' Since the inside of the vaporization tube 4 is heated to a predetermined temperature by the preheating heater 17 in advance, the kerosene vapor becomes finer particles in the vaporization tube 4, and mixes with the combustion air to become a mixed gas that is easy to ignite. By igniting it at the flame port 18' of the burner head 18, blue flame combustion is achieved. The heating power is adjusted by rotating the adjustment knob 5 to adjust the amount of combustion air blown, thereby changing the blowing pressure applied to the oil level regulator 8 and supplying fuel from the fuel nozzle 11. This is done so that the amount of air is approximately proportional to the amount of air blown.
The fire is extinguished by stopping the fan 3 to eliminate blowing pressure, and by stopping the pushing up of kerosene from the oil level regulator 8 to the fuel nozzle 11.

In such fan heaters, the presence or absence of ignition is electrically detected by a flame detection rod (flame rod) located in the flame port 18', but the combustion flame is unstable at the initial stage of ignition, and the flame Since the detection rod (flame rod) has not yet become red hot, the ion current is low, and if combustion continues for a while, the combustion flame stabilizes, the flame rod becomes red hot, and the ion current tends to increase. Therefore, in the past, the sensitivity of flame rods was set high so that even a small ion current at the time of ignition could be detected. but,
If the flame sensitivity is set high so that ignition can be detected even with a small ion current at the time of ignition, it will be difficult to detect abnormal combustion such as red flame during steady combustion (the ion current will also be low), making it difficult to extinguish the fire in a timely manner. On the other hand, if the flame sensitivity is set low to sharply detect abnormalities during steady combustion and extinguish the fire, the small ion current at the time of ignition will be difficult to detect, resulting in a high number of ``mis-ignition'' determinations. Not being able to detect abnormal combustion is very dangerous, and on the other hand, if there are many ``misfires'', you will have to ignite the engine many times, and the ignition timer may not ignite, which is very inconvenient. It is. In order to solve these drawbacks, the present invention has devised a flame detection circuit that automatically switches the flame rod sensitivity to high sensitivity during ignition and low sensitivity during combustion operation.

Below, specific examples of the flame detection circuit will be explained in the second and third examples.
This will be explained according to the diagram. In FIG. 2, 21 is a power plug, 22 is a power fuse, 23 is an operation switch, and 24 is a reset switch. 25 is a control circuit section, as shown in detail in Fig. 3, the secondary output of the transformer is rectified by a diode bridge 26, smoothed by a capacitor C1, and regulated by a resistor R1, a constant voltage diode D1, and a transistor Q1. and relays RY1, RY2, RY3, comparator
IC-1 Supplies power to IC-2 and IC-3. When the power plug 21 is connected to a power outlet, the operation switch 23 is closed, and the reset switch 24 is closed, the control circuit 25 is energized. At this time, the output of comparator IC-2 shown in the lower right of Fig. 3 is "H" because no charge is applied to capacitor C8.
Then, transistor Q6 turns on. Therefore, power plug LED2 lights up and relay RY3 turns ON.
Contact RY3-1 (Fig. 2) of RY3 closes to the NO side, and even if the reset switch 24 is opened, the relay is not activated.
RY3 is self-maintaining. Since the temperature of the vaporizer cylinder 4 is still low at the initial stage of energization, the positive temperature coefficient thermistor PTC (shown in the upper center of Figure 3) for temperature detection has a low resistance.
The output of IC-1 is "L". Therefore, relay RY1 and relay RY2 are OFF. So contact RY ₁ - ₁ N.
Only the preheating heater 17 is energized through the C. side. Eventually, the preheating heater 17 heats the vaporization cylinder 4 and PTC becomes high resistance, and the output of IC-1 is reversed to "H", and the relay RY1 and relay RY2 turns on at the same time. In other words, relay contact RY ₁ - ₁ is NO
On the side, relay contact RY ₂ - ₁ switches to the NO side, so the preheating heater turns OFF, and the combustion motor 2 blows kerosene into the vaporizer cylinder 4 together with the primary air, instantly turning off the kerosene. Vaporize and igniter there
IGN discharges and ignites. The igniter has a built-in timer and will stop discharging in about 20 seconds. Also, turn on the convection blower FM. at the same time
The output of IC-1 starts charging the capacitor C8 through diode D5 and resistor R11, and after the "misfire time" has elapsed, the output of IC-2 is reversed to "L". However, if ignition occurs and flame is detected within the "mis-ignition time" (charging time of capacitor C8), the output of IC-3 becomes "H" and transistor Q6 is turned on through diode D7, so relay RY3 is turned on. continue. If the ignition does not occur within the "mis-ignition time", the output of IC-3 remains "L", so transistor Q6 turns OFF.
However, since relay RY3 is also turned off, self-holding is cut off, all energization stops, and the power lamp also goes out.

Here, the operation of the flame detection part will be explained. When there is no flame, connect resistor R17 to the (-) input of IC-3.
Since a voltage higher than the (+) input of IC-3 is applied, the output of IC-3 is "L". When ignited, an ionic current flows from the flame rod (flame detection rod) 27 toward the burner section 28, and the potential at the junction between the capacitor C4 and the resistor R15 is lowered. In other words, the (-) input potential of IC-3 is lowered, and the output of IC-3 is inverted to "H". When the output of IC-3 becomes "H", combustion lamp LED1 turns on, and diode D7 causes RY3 to turn on.
continues to be ON, and relay RY2 is activated by diode D8.
remains ON. Also, diode D9 and resistor R3
0. After delaying for a few seconds (until the flame stabilizes) with capacitor C7, turn on transistor Q4,
Slightly lower the (+) input voltage of IC-3.
When the (+) input voltage is lowered, the difference with the (-) input voltage of IC-3 during steady combustion becomes smaller, causing abnormal combustion and reducing the ion current, causing IC-3 to
-It can be quickly detected when the (-) input voltage of 3 becomes high. In other words, if the (+) input voltage of IC-3 is low, the difference with the (-) input voltage is small, so even a slight increase in the (-) input voltage due to a decrease in ion current can be detected. 3, when the (+) input voltage is high, there is a large difference from the (-) input voltage, so it cannot be detected unless there is a significant increase in the (-) input voltage due to a significant decrease in the ion current (or a very small ion current). In other words, when the (+) input voltage of IC-3 is lowered by the transistor Q4, the frame sensitivity becomes lower.
If the resistance value of the resistor R21 is increased, the difference in frame sensitivity can be increased.

As mentioned above, when abnormal combustion occurs and the output of IC-3 is reversed to "L", transistor Q6 and relay RY3 are _sequentially turned off via diode D7, and relay contact _RY3-1 is opened, so energization is stopped. Since the fan 3 also stops rotating, the fire is extinguished.

As mentioned above, the diode D9, the resistors R18, R
30. By using capacitor C7 and transistor Q4, the (+) input voltage of IC-3 is high during ignition, and the output is likely to be "H" (flame sensitivity is high), and transistor Q4 is ON during combustion. As a result, the (+) input voltage is lowered by the resistor R21, and the output can easily become "L" (frame sensitivity is low). Chattering of IC-3 can also be prevented by delaying with capacitor C7. Diode D10 turns off the power
This is for discharging capacitor C7 when Note that the above resistor R30, capacitor _C7 and diode D
10 constitutes a time constant circuit for preventing chattering, and transistor _Q4 serves as switching means. Further, resistors R ₂₁ , R ₂₂ and R ₂₄ form a reference voltage setting circuit.

The circuit of the present invention can be used in oil gasification fan heaters, gas fan heaters, FF type oil gasification hot air heaters, FF type gas hot air heaters, gas stoves, oil gasification stoves, hot water boilers, and the like.

As mentioned above, the flame detection circuit of the present invention changes the sensitivity of the flame after confirming that a flame has been formed by ignition, so it can accurately detect "mis-ignition" and "abnormal combustion" in a combustion machine. can be detected.

Although the flame is unstable immediately after ignition, since the flame sensitivity is changed after confirming the stability of the flame after ignition using a time constant circuit, malfunctions can be reliably prevented.

By the way, timing starts at the same time as the ignition device is activated.
If you want to change the flame sensitivity after a certain period of time, you must set the period of time during which stable combustion is always occurring, and do not change the sensitivity until a considerable amount of time has actually passed after stable combustion has been achieved. become. Therefore, if abnormal combustion occurs immediately after entering a stable combustion state, it will not be detectable for a considerable period of time until the sensitivity changes.

In contrast, according to the present invention, abnormal combustion as described above can be detected immediately.

[Brief explanation of the drawing]

FIG. 1: A schematic cross-sectional configuration diagram of an oil gasification fan heater, FIG. 2: A block diagram of essential parts of the fan heater according to the present invention, and FIG. 3: A detailed circuit diagram of its control circuit 25. Symbol, R1, R2...: Resistor, D1, D2...: Diode, C1, C2...: Capacitor, IC-
1, IC-2, IC-3...: Comparator, RY1,
RY2, RY3: Relay, Q1, Q2...: Transistor, T: Transformer, Ne: Neon tube, 27: Frame rod.

Claims (1)

[Claims] 1. ``Ignition'' is performed by detecting flame with a flame rod.
This is a combustion machine that performs sequence control by sending "combustion" information to a control circuit, in which the rectified output of the flame rod is connected to one input terminal of a comparator, and the reference voltage from a reference voltage setting circuit is connected to the other input terminal of the comparator. In a flame detection circuit in which a voltage is connected and the output of the comparator is used as a flame detection output, the reference voltage setting circuit is provided with a switching means for changing the output reference voltage, and the output of the comparator is used as an input for chittering. A flame detection circuit characterized in that a time constant circuit for prevention is provided, and the switching means is switched by the output of the time constant circuit.